Schottky diodes are familiar semiconductor devices formed, typically, by a metal-semiconductor junction. Persons of skill in the art understand that the “metal” used in forming the Schottky diode or junction may be other than a pure metal and may also be an alloy or mixture of various metals and/or semi-metals, as for examples and not intended to be limiting, silicides of a wide variety of metals. Accordingly, the terms “metal” and “silicide” as used herein are intended to include such variations and other suitable conductors. A wide variety of semiconductors can be used in forming Schottky diodes, such as for example and not intended to be limiting, types IV, III-V and II-VI semiconductors, organic semiconductors, and layered devices such as semiconductor-on-insulator (SOI) devices. Accordingly, the term “semiconductor” is intended to include these and other materials suitable for forming Schottky diodes.
The Schottky diode is generally thought of as a majority carrier device since carrier recombination is ordinarily not involved in its operation. Compared to ordinary PN junction diodes, Schottky diodes have very low forward drop and fast switching speed, which makes them very useful in a number of familiar applications. However, their usefulness is often limited because, when reverse biased, the leakage current is relatively high and increases rapidly with increasing voltage. This makes it difficult to achieve Schottky diodes with high breakdown voltages using ordinary semiconductor materials. Despite the advantages of low forward drop and very fast switching speeds, Schottky diodes often cannot be employed in applications where their higher reverse leakage currents can degrade overall circuit performance.
Accordingly, it is desirable to provide a new type of Schottky diode with improved reverse characteristics, and more particularly, a Schottky diode suitable for operation at higher voltages and with lower leakage at a given voltage than has been achievable in the prior art for the same semiconductor materials. In addition, it is desirable to provide a structure and method for fabricating Schottky diodes in very thin epitaxial layers suitable for use with complex power devices and/or integrated circuits and especially with state of the art Smart Power technologies. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.